Granular Flow in a Planetary Mixer

Hiseman, M.J.P.; Laurent, B.F.C.; Bridgwater, J.; Wilson, D.I.; Parker, D.J.; North, Nigel C.; Merrifield, D.R.

doi:10.1205/026387602320224012

Cited by 31 publications

(25 citation statements)

References 3 publications

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“…. , Plank et al, 2003, c) Niro Pellmix (Knight et al, 2000, Schaefer et al, 1993, d) Collette Gral (Faure et al, 1999), e) Zanchetta (Nilpawar et al, 2006), f) custom design vHSM (Tu et al, 2009, Knight et al, 2001, Bridson et al, 2007, g) planetary mixer (Hiseman et al, 2002), and h) cyclomix mixer granulator (Ng et al, 2007a) 6.1 Properties of each compartment from experimental PEPT data for the two-CM and multi-CM: occupied volume vol, occupancy occ, average particle velocity v p , average dimensionless particle velocity v …”

Section: Granulation Processes As Classified Bymentioning

confidence: 99%

“…Work on understanding powder flow has mainly focussed on industrial vHSM with rotating impellers at the base e.g. Fielder, Diosna, Collette Gral, Niro Pellmix (Knight et al, 2000, Schaefer et al, 1993, though other studies also include the cyclomix (Ng et al, 2007a,b, Hassanpour et al, 2009) and planetary mixer (Hiseman et al, 2002) (see Figure 1.5). A number of researchers have designed custom mixers in order to simplify complex flow , Plank et al, 2003, c) Niro Pellmix (Knight et al, 2000, Schaefer et al, 1993, d) Collette Gral (Faure et al, 1999), e) Zanchetta (Nilpawar et al, 2006), f) custom design vHSM (Tu et al, 2009, Knight et al, 2001, Bridson et al, 2007, g) planetary mixer (Hiseman et al, 2002), and h) cyclomix mixer granulator (Ng et al, 2007a) Knight et al (2000) patterns (see Figure 1.6).…”

Section: Granulation Equipmentmentioning

confidence: 99%

“…Bumping regime (also referred as pulsing in a horizontal mixer (Laurent, 2006) or shunting in a planetary mixer (Hiseman et al, 2002)): At low impeller speeds, the powder bed surface appears to remain horizontal as the bed is "bumped" in sequence to the passage of the blade beneath it. Quantitative definitions of these flow regimes have been based on the measured values of powder velocity as a function of impeller speed.…”

Section: Powder Flow Regime Mapmentioning

confidence: 99%

“…Impeller design also has significant impact on the flow with the planetary mixer "K-beater" producing highly complex flow patterns (Hiseman et al, 2002).…”

Section: Impeller and Mixer Designmentioning

confidence: 99%

“…Research has been conducted using the PEPT to delineate the powder flows in various process equipments, including ploughshare mixers (Jones andBridgwater, 1998, Forrest et al, 2003), planetary mixers (Hiseman et al, 2002), rotary kilns (Parker et al, 1997, Lim et al, 2003, Kuo et al, 2003 and single-bladed horizontal mixer (Laurent and Bridgwater, 2000).…”

Section: Techniques Of Studying Powder Flowmentioning

confidence: 99%

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Powder flow in vertical high shear mixer granulators

Tran¹

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An integral component in understanding the fundamental mechanisms of granulation is the powder flow behaviour within mixer granulators. All three classes of granulation rate processes: wetting and nucleation, consolidation and coalescence, and attrition and breakage require detailed knowledge of flow fields in mixing systems to enable rational approaches to the prediction of granule attributes. The three objectives of this thesis are to 1) develop a powder flow regime map to characterise the powder flow field, 2) investigate the effect of impeller speed, powder cohesion and blade-rake angle on powder flow and mixing behaviour and, 3) outline a framework for compartment models of vertical-axis high shear mixer (vHSM) granulators.In the development of the powder flow regime map, two distinct regimes were identified. Ideal roping regime occurs at high impeller speeds when the rotating blades pushes the powder out and up the mixer wall, and then back down the free surface forming the "roping" flow pattern. This stable flow behaviour promotes high vertical bed turnover which is essential for controlled granulation. In this regime, the powder in the blade region has sufficient rotational inertia to overcome gravitational forces (i.e. powder Froude number greater than unity). If this criterion is not met, the mixing system remains in the undesirable bumping regime. This regime is characterised by poor bed turnover and non-uniform shear distribution within the powder bed. In the bumping regime, multiple transitional states are observed with increasing impeller speeds for this particular system, which has not been fully characterised in the literature before. An explanation for the observed apparent roping behaviour based on bed resonance is given. These intermediary transitional states can be differentiated by blade-powder interactions.From these observations, a powder flow regime map for vertical-axis mixer granulators is proposed based on two dimensionless groups: powder Froude number, the ratio of the powder rotational inertial to gravitational forces and the Bed Resonance number, which characterises the interaction of the bulk motion of the powder bed with the passage of impeller blades beneath it. The regime map was validated by experimental results utilising ii iii the well-established, non-invasive tracking technique of Positron Emission Particle Tracking (PEPT) and torque measurements.Investigations into the effect of impeller speed, powder cohesion and blade-rake angle on powder flow and mixing behaviour were conducted using PEPT. Results showed that powder velocity, bed porosity and shear rates varied spatially within the mixer granulator. Studies of the stable roping regime revealed that the average powder velocity in the impeller zone was 1.66 m/s (≈25% of the impeller tip speed). In comparison, the average powder velocity in the circulation and surface zone was approximately half of the impeller zone at 0.9 and 0.74 m/s, respectively (12% and 11% of the impeller tip speed). With the addition of mois...

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Section: Granulation Processes As Classified Bymentioning

confidence: 99%

Section: Granulation Equipmentmentioning

confidence: 99%

Section: Powder Flow Regime Mapmentioning

confidence: 99%

“…Impeller design also has significant impact on the flow with the planetary mixer "K-beater" producing highly complex flow patterns (Hiseman et al, 2002).…”

Section: Impeller and Mixer Designmentioning

confidence: 99%

Section: Techniques Of Studying Powder Flowmentioning

confidence: 99%

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Powder flow in vertical high shear mixer granulators

Tran¹

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Laminar Mixing Fundamentals

Cullen

Misra²

2015

Pharmaceutical Blending and Mixing

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Granular flow fields in vertical high shear mixer granulators

Kwan

Ding

et al. 2007

AIChE Journal

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This study aims to elucidate some basic features of the granular flow field in a conical frustum-shaped vertical high shear mixer granulator by using the Positron Emission Particle Tracking technique. The tested range of particle size (d 50 ¼ 23, 43, and 60 lm) and shape as quantified by the angle of internal friction (268 and 388) have a negligible effect on the granular flow field in the mixer granulator. Density of particle imposes great influence on the flow field where reducing density from 2600 to 700 kg m 23 increase the tangential velocity by 1.95 time. Decreasing fill level from 3.5 to 0.9 kg increases the tangential velocity by a factor of 1.19. No obvious discrepancy in the solids motion is seen between machines of 1 and 5 L capacity and both machines have similar mixing and dispersion with constant tip speed criterion.

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Granular Flow in a Planetary Mixer

Cited by 31 publications

References 3 publications

Powder flow in vertical high shear mixer granulators

Powder flow in vertical high shear mixer granulators

Laminar Mixing Fundamentals

Granular flow fields in vertical high shear mixer granulators

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